Various forms of tools and mechanisms have been proposed in the past for compressing valve springs of internal combustion engines so as to facilitate the removal and installation of rocker arms and lash adjusters. For example, U.S. Pat. No. 4,176,435, issued on Dec. 4, 1979 to John H. Castoe discloses a device comprising a tubular sleeve pivotally supported on an elongated leverage arm. The sleeve is formed with a working surface adapted to engage a valve spring while the leverage arm has one end engageable with a fixed support attached to the cylinder head. By application of a downward force at the free end of the leverage arm, the valve spring is compressed sufficiently to remove or install a rocker arm.
Another example of a tool proposed for use in compressing valve springs can be seen in U.S. Pat. No. 4,446,608, issued on May 8, 1984 in the name of Joel S. Johnson. This particular tool also includes a lever one end of which is provided with a depressor member, an attachment link, and a support leg, all three of which are pivotally connected to the lever at spaced points. In operation, a support bracket assembly provided with pivot shafts is first attached to the cylinder head. Afterwards, the attachment link is hooked under one of the pivot shafts of the support bracket assembly to provide a fulcrum and the depressor member is positioned in contact with the top of the a valve spring cap. This is followed by applying a downward force on the free end of the lever resulting in compression of the valve spring for removal of the rocker arm. In this case, the support leg serves as a stop that swings into engagement with a plate portion of the support bracket assembly to permit both hands of the operator to be used for removal or installation of the rocker arm, lash adjuster, and the valve itself, if desired.
U.S. Pat. No. 2,524,949, issued on Oct. 10, 1950 in the name of Chester P. Applegate is still another example of a tool which has been proposed for use in compressing the valve springs of an internal combustion engine. In this instance, the tool takes the form of a mechanism which is mounted on a work bench or table and includes appropriate brackets and clamps for supporting a cylinder head containing the valves. The mechanism is provided with a jack stand which is slidable along support shafts into a desired position above the valve that is to be removed after which the lever of the jack stand is depressed and the valve spring retainer is contacted. The valve head is then restrained from movement by a part of the jack stand located below the cylinder head and the lever is further depressed to compress the valve spring so as to allow removal of a pin and valve cap and finally permitting the valve spring to be removed from the cylinder head.
As explained above, each of the tools described above serves to compress a valve spring so as to facilitate the removal or installation of a rocker arm, lash adjuster and/or a valve of the cylinder head. However, one common problem with each of the tools is that the tool is required to be combined with a support bracket assembly of some type which must be fastened to the cylinder head. In each instance, the support bracket assembly must first be secured to the cylinder head before the tool can be used to perform its function, and afterwards it must be disassembled from the cylinder head once the job is completed. Accordingly, this not only increases the cost of the tool but also increases the time spent by the person using the tool to complete the job.
Another problem with the tool disclosed in the Johnson '608 patent mentioned above is that, in order to readily position or release the attachment link (which is shaped as a hook) from the pivot shafts, it would seem that one will need to reach under the tool and use his fingers to manually provide engagement with or release from the pivot shaft. Obviously, this could be difficult to accomplish at times particularly if the person using the tool has large fingers and is working in an area that is limited in size.